The present invention is based on a method for detecting a glow plug replacement.
DE 10 2010 040 682 A1 discloses a known method for detecting the replacement of glow plugs, in which at least one electrical parameter of a glow plug is determined and compared with a stored value during a driving cycle, said stored value having been measured under the same conditions in an earlier driving cycle. If the two values differ from each other by more than an allowed threshold value, it is concluded that a glow plug replacement had taken place. A similar method is known from DE 10 2008 007 398 A1.
The automatic detection of a glow plug replacement is essential because modern glow plug control units adjust the temperature of a glow plug using a set of plug-specific control parameters. If the plug-specific control parameters are used unchanged after a glow plug replacement, there is the risk that the glow plug is operated at temperatures that are too low, resulting in suboptimal combustion of the fuel, or at temperatures that are too high, resulting in damage to the glow plug.
If a glow plug replacement is detected, a reminder to enter new control parameters may be put out or the glow plug control unit may automatically determine new control parameters by heating up the glow plug under controlled conditions. Such a determination is relatively complicated. To achieve this, a glow plug is typically operated for about one minute with a defined heating output while the vehicle is parking. For this reason, it is not practicable to determine new control parameters or subject the control parameters to an extensive check whenever the vehicle is started.